Roof-framing calculator



G. E. MARTIN ET AL ROOF-FRAMING CALCULATOR Feb. 13, l1951 2 Sheets-Sheet l Filed Sept. 9, 1949 Feb. 13, 1951 G. E. MARTlN ETAL 2,541,596

ROOF-FRAMING CALCULATOR Filed Sept. 9, 1949 2 Sheets-Sheet 2 Patented Feb. 13, 1951 ROOF-FRAMING CALCULATOR Gilbert E. Martin and Warren E. Lopez, New Orleans, La.; said Martin assigner to said Lopez Application September 9, 1949, Serial No. 114,854

1 Claim.

Our invention relates to improvements in disc calculators, and more particularly to a more eilicient and easily-used calculator for quickly and accurately ascertaining the correct angles for the various cuts required to be made in the structural components of roofs with the aid of a framing square, the primary object of the invention being to provide a device of this kind which furnishes all of the information as to the various cuts to be made in the components of a roof of known lpitch from a single setting of the device.

Anothel` important object of the invention is the provision of a device of the above-indicated character which is capable of a plurality of suchr single settings correspondingto roofs of different pitches, and involves means for locking the same in any of such settings.

A further important object of the invention is the provision of a device of the character indicated above which is of simple and mechanicallyadequate construction, so as to be capable of being made in a serviceable and attractive form at relatively low cost.

Other important objects and advantageous features of our invention will be apparent from the following description and accompanying drawings, wherein, merely for purposes of illustration herein, a specific embodiment of the invention is set forth in detail.

In the drawings:

Figure 1 is a top plan view, showing a setting of the device;

Figure 2 is a transv'se vertical section taken on the line 2--2 of Figure '1;

Figure 3 is an enlarged horizontal section taken on the line 3 3 of Figure 2 and showing the markings on the rotary disc;

Figure 4 is an enlarged perspective view of the pivot.

Referring in detail to the drawings, the numeral 5 designates a at circular base of appropriate material formed with a peripheral groove 6 dening a shoulder 'I at its lower side. Seated in the groove 6 upon the shoulder 1 is the depending rim flange 8 of the circular top plate 9, the top plate 9 being thereby spaced upwardly from the base 5 and secured in place by screws or the like I0 traversing the flange 8 and entering the base. The top plate 9 is opaque and has openings, hereinafter described, which are covered by a transparent plate II secured to the under side of the top plate.

A pivot element, generally designated I2, cornprises, as clearly shown in Figure 4, upper and lower axially-aligned cylindrical portions I3 and I4, respectively, projecting centrally from the upper and lower sides, respectively, of the square plate i5. The lower end of the lower portion I4 is rounded, as indicated at I6, to seat rotatably in a concavity I'I formed in the top of the base 5, as shown in Figure 2. The upper end of the upper portion I3 is provided with an axial, threaded bore I8. The pivot element I2 is so proportioned that with the rounded lower end of the portion I4 seated in the base concavity I'I, the square I5 is positioned on a level midway between the transparent plate II and the base i5, with the upper portion I3 projecting upwardly through a journal hole I9 provided in the top plate 9. Upper and lower washers 20 and 2 I, respectively larger than the square plate I5, are circumposed on the pivot element portions I3 and I4 and substantially take up the spaces between the upper and lower sides of the square plate I5 and the lower surface of the transparent plate II and the upper surface oi the base 5, respectively, whereby the pivot element I2 is restricted to a small amount of vertical movement.

A knob 22 having a cavity 23 in its under side receiving the upper end of the upper pivot portion I3 is vertically traversed by a screw 24 threaded into the bore I8 which holds the knob xedly on the pivot element with the under side of the knob close to the upper surface of the top plate 9.

The rotary disc 25 is a plane hat circular disc whose peripheral edge 2t is squared and is concentrically spaced from the rim flange of the top plate S. The disc Z5 is oi the saine thickness at its center as the pivot element plate I5 so as to turn snugly between the washers 2E! and 2l and is formed with a square hole 2l coniormably receiving the square plate I5, whereby the disc 25 is rotatable with the pivot element i2 as the knob 22 is manually rotated to selectively position or set the disc 25. It will be noted that the hole 2'! is oi the same polygonal shape as said plate I5. For holding the disc 25 in a desired setting, a set screw 28 is threaded horizontally .through the rim nange 8 to bear against the peripheral edge 26 and may be loosened or tightened by manuallj,r turning its head 29 which is positioned radially outwardly from the rim flange 8.

The top plate 9, as shown in Figure 1, is formed therethrough with a plurality ci openings exposing the upper surface of the disc 25 through the transparent p-late or sheet I I, the openings being arranged in predetermined groups and positions relative to each other and to markings on the disc 25.

Reading clockwise :from the upper left portion of three segmental roof pitch-selecting openings 3G, 3! and 32 which are arranged to expose corresponding arcs of related indicia 3U', 3| and 32', respectively, provided on the disc 25. The outer arc 30 designates the selected roof pitch, while the intermediate arc 3i designates the proper length of the selected gable cripples for 16 inches on center, while the inner arc 32 designates the proper length of the gable cripples for 24 inches on center. The registration of the outer pitch-selecting opening 3G with the selected one of the indicia of the outer arc 3G' sets the disc 25 for all of the other information supplied by the device. When. so set, the set screw 28 is tightened to hold the disc 25 in position so that correct reading of the device in the set position is assured.

With the hole 3G registered with the selected indicia of the are another outer group oonsisting of radially-aligned holes 33, 34, 35 and 35 expose related ones of the indicia of arcs 33', 34', 35 and 36 on the disc giving the lengths of common rafters. Also aligned with this group of openings is inner opening 3l exposing an arc 3l on the disc 25 showing the correct collar brace cut; and another inner opening 3B exposing an arc on the disc showing the correct length of jacks for twenty-four inches oi'center.

Another outer group consisting' of radiallyaligned holes 3Q, 4l and expose individual indicia of arcs fill", 4l and 42', respectively, en the disc 25, showing correct hip lengths. An inner opening A3 aligned with this group exposes one of the indicia on an inner aro 43 to show the correct hip cut, and another inner are 44' to show the correct jack length for sixteen inches on center.

The three groups described above are spaced at about 120 apart. Further inner openings, spaced eduidistantly between the three outer groups described above, include, in clockwise order. the inner openings A5, 45 and 41, exposing indicia at equallycircumferentiallyspaced points on an inner circle 43 on the disc 25, the opening @Si showing the correct cut for gable cripples, the opening 46 the correct cut for sheathing, and the opening 41 the correct cut for the jacks.

As herein disclosed., the device has ten roof pitch settings, the arc 3D on the disc 25 being' composed of ten ciicurnferentially-spaced triangles lli-' having numerals 5d, 5l and 52 designating lengths of the bases, altitudes and hypotenuses, respectively, of the triangles, the triangles ranging from a right triangle. In all instances the indicia of the outer and inner arcs are radially aligned in the various groups.

Common rafters When the device is set, the information exposed by the pitch setting opening 353 is the plomb and level cut of the common rafter of 12 inches run, with the pitch determining the rise. for the common rafters is the numeral 53 alongside the relating to different runs. The by the openings 33 to 36 give the lengths for tll..V somtnon rafters as indicated by the numerals In determining the cut of a raiter having a run other than those indicated by the numerals E53, the numeral 53 closest to the desired run is taken and one foot is either added or subtracted as many times as the run is greater or less than the given run. For example, the out for a desired 13-foot run can be obtained by laying oiT on the timber the given length for 12 feet and then extending the length one-times-one foot. In the case of a desired run of 19 feet, the solution would be to take the 2G-foot run, subtract 1 foot of given run, and obtain 19 feet as the desired run. If the desired run should be 15 feet, ten feet of given run is taken and 5 feet is added thereto. The cuts for fractional lengths may be similarly obtained.

Hip rafters Hip or valley rafters normally have a run of 16.97 inches to every foot of run on the common rafters, so that for practical purposes 17 inches is used for the level cut just as a 12-inch cut is used for the common rafters, The side cuts for the hip rafters are found exposed in the opening 43, and the lengths in the openings 39 to 52. The plumb cut and the intermediate given lengths are obtained as the case of the common rafters.

Jack rafters rlhe plumb andlevel cuts for the jack rafters are obtained as` in the case of the common rafters, but the side cuts of the jackrafters are obtained from the opening 41, the lengths of the jack rafters being determined by the number of feet on center at which they are spaced. The lengths given in the opening 44'. are for the shortest jack. The length of the longest jack rafter may be obtained by subtracting the shortest jack rafter length from the related common rafter length. To get the length of the next to the shortestjack rafter, the length given in the opening 134 is. added to the length of the shortest jack rafter.

Gable cripples The openings 3| and 32 givethe lengthsfor the shortest cripples for the ori-center arrangements indicated alongside these openings. If working from center, the longest cripple thatwill fit in the gable peak is measured andsfroin this is subtracted the givenvlen-gth nieasuringfromthe `peak down, and-the` remainder is-the-length of The end cuts for collar braces are obtained from the opening 31, but the length for the collar braces is not given, since this depends upon the height from the ceiling joist desired. The same cut can be used for weatherboard or anything running horizontal and intersecting the roof in its rake.

Sheathing The cuts for sheathing are obtained through the opening 45 in the disc 25 which relates to placing sheathing around'hips or in valleys.

We claim:

In a calculator, a` base, a plate arranged` in spaced parallel relation toand xedly supported onssaid base, a circular disk positionedbetween said base andsaidlplate, said dish being formed withn a polygonal lcenter hole, a pivot element ex- 5 tending through the hole in the disk, said pivot element having one end journalled on said base and its other end extending through' an opening formed in said plate and projecting outwardly beyond said plate, said pivot element having a lpolygonal portion spaced from its ends and positioned in said polygonal center hole whereby said pivot element and said disk are connected for rotation together, spacing means positioned on said pivot element at opposite sides of said poly- 10 gonal portion and spacing said polygonal portion and said disk from said -base and from said plate, and a disk rotating knob larger in diameter than and xed on the said other end of the pivot element and bearing against the 5 outer side of said plate.

GILBERT E. MARTIN. WARREN E. LOPEZ.

REFERENCES CITED The following references are of record in the le of this patent: 

